1. Field of Invention
The present invention relates generally to information retrieval systems and methods, and more particularly, to the dynamic generation of context dependent navigation information between documents in an information retrieval system.
2. Background of the Invention
The World Wide Web is today's most commonly used information retrieval system. One of the distinguishing features of documents on the World Wide Web (and of intranets) is the use of hypertext links that associate a portion of one document with another document, which may be located on any computer system coupled to the Internet or a local intranet and supporting the appropriate communication protocols. A hypertext link (or simply `link`) is typically defined by a selected term or set of terms in a source document, and the network location of the target document, expressed as a uniform resource locator or URL. A hypertext link may also be associated with portions of images or control features such as buttons, menus, and the like. Hypertext links allow a user to navigate from the source document to the target document by activation of the link and thereby retrieve the target document in this fashion.
In conventional hypertext documents, links are statically defined. This means that either the term(s) used in the source document from which the link originates (the anchors), or the target document of the link are determined when the source document is created. For most hypertext documents, the links are completely static: the publisher manually determines which terms of a source document will be the anchors and which documents will be the targets. When a user accesses the source document, the links are provided exactly as defined by the publisher.
This paradigm has several significant drawbacks. First, because the links are manually defined, they require manual effort to create, update, or remove from a document. The publisher must decide which terms (or other portions of a document, e.g., images) will be used, and which documents will be the targets. The publisher must exercise editorial judgment in selecting both these terms in the source document, and particularly in selecting the target documents. However, because the available content on the Internet, and in most intranets, is continuously changing, the publisher is unlikely to know all of the possible target documents that may be relevant for a given link.
Second, once the links are defined by the publisher, the user who accesses the source document has no ability to redefine them.
Third, a link can only refer to documents that exist at the time the link is defined. Thus, after the source document and its links are defined, it can be immediately out of date if it does not contain links to relevant documents that have been subsequently created. Further, as new content emerges on the Internet or local intranet, manual changes by the publisher are needed to update the existing links to refer to such new content.
Systems do exist on the World Wide Web which present new links to a user in response to user inquiries, such as Internet search engines like AltaVista.TM.. However, these systems present a very limited navigation paradigm. FIG. 1 illustrates the iterative navigation paradigm and usage flow of conventional search engines. With a search engine, the user must manually enter a set of keyword search terms which the user believes are related to a topic of interest. In response, the search engine returns a document with links to other documents (here D1 . . . Dn) which satisfy the query, and hopefully provide information related to the user's topic of interest. Once the user accesses one of the referenced documents Dn, however, he is out of the `scope` of the search engine, and any further navigation is limited to the links to other documents J1 . . . Jn that have been statically defined in the referenced document Dn (and to the children of such documents). To access any of the other documents that satisfy the user's initial query, the user must navigate back to the search engine results, and proceed from there, iteratively accessing the search result documents D one by one. If the user wants to refine or modify the query, the user returns to the search engine and inputs a new query, and generates a completely new set of search results (which may, by the vagaries of search engines, result in a completely different set of documents).
The problem with this search paradigm is that search engine's capabilities are only available at the initial point of the user inputting their search inquiry. Once the user accesses a referenced document in the search result set, the search engine is incapable of providing any analysis of the referenced document, and in particular is unable to dynamically analyze the target document's content or generate any new links from that target document to other documents that may be available or relevant. Again, the user is limited to only those links in the target document that have been established by the publisher.
Accordingly, it is desirable to provide a system and method of navigation of documents in an information retrieval system generally, and on the World Wide Web and intranets particularly, that can dynamically analyze the contents of any target document being accessed by a user and generate new hypertext links to other documents that may be relevant to the target document.